A dwindling number of developers of large-scale power plants in the deserts of the western U.S. slated to make electricity by converting the sun's heat into power.
Topping out at over 600 feet, the Crescent Dunes solar tower will rank among the tallest structures in Nevada. The tower has an ultimate height of some 60 stories. It has to be that tall to absorb the reflected light from some 10,000 billboard-sized mirrors that will be installed in concentric half circles around its base. Once complete, the pillar will be capped with a collector, at which all those mirrors will point, focusing the sun's rays. Where the reflected rays converge, temperatures will hit over 1,000 degrees Fahrenheit.
This thermal energy can be used immediately to generate steam in a turbine. Or the heat can be stored, absorbed in molten salts kept in insulated containers.
The Santa Monica, Calif. company is building the tower that will sit at the heart of its $900 million Crescent Dunes Solar Energy Project. Smith emphasized that while the tower attracts a lot of attention, it may be that the project's ability to store the sun's energy will become its most competitive virtue, particularly at a time when as the solar market is being rocked by plummeting prices for photovoltaic panels, a competing technology.
Tonopah's design is the largest of its kind, building on precedents set by a pair of smaller solar towers that have been operating in Spain and Arizona. The current project will use thousands of computer-operated poster-size mirrors aiming sunlight at a tower that absorbs it as heat. After that the absorbed heat is stored in the molten salt, which can be used immediately to boil water, generating steam that turns a conventional turbine and generator. Hot salt can also be used to retain the heat for many hours for later use. BrightSource heats water that can be used immediately as steam or to heat salt for storage.
The plants rely on salt because it can store far more heat than water can. But once molten, it must be kept that way or it will freeze to a solid in part of the plant where it will be difficult to melt again.
This comes after the failure of Solyndra, which was granted $535 million federal loan guarantee to commercialize a novel design for tube-based solar panels. Critics have gone on the warpath, questioning practically all renewable-energy projects that have received federal funds. SolarReserve was offered a $737 million loan guarantee by the DOE last May to help build the Tonopah project.
The 110 MW solar thermal power tower plant utilizing the advanced molten salt system technology from United Technologies Corporation when completed, the facility will supply approximately 480,000 megawatt hours annually of clean, renewable electricity. It is financially backed by a signed 25-year power purchase agreement with NV Energy. Once constructed, it will power up to 75,000 homes during peak electricity periods.
If solar energy is eventually going to matter — that is, generate a significant portion of the nation’s electricity — the industry must overcome a major stumbling block, experts say: finding a way to store it for use when the sun isn’t shining. That challenge seems to be creating an opening for a different form of power, solar thermal, which makes electricity by using the sun’s heat to boil water. The water can be used to heat salt that stores the energy until later
Sources:
Digg Topnews
NYTimes.com
Topping out at over 600 feet, the Crescent Dunes solar tower will rank among the tallest structures in Nevada. The tower has an ultimate height of some 60 stories. It has to be that tall to absorb the reflected light from some 10,000 billboard-sized mirrors that will be installed in concentric half circles around its base. Once complete, the pillar will be capped with a collector, at which all those mirrors will point, focusing the sun's rays. Where the reflected rays converge, temperatures will hit over 1,000 degrees Fahrenheit.
This thermal energy can be used immediately to generate steam in a turbine. Or the heat can be stored, absorbed in molten salts kept in insulated containers.
The Santa Monica, Calif. company is building the tower that will sit at the heart of its $900 million Crescent Dunes Solar Energy Project. Smith emphasized that while the tower attracts a lot of attention, it may be that the project's ability to store the sun's energy will become its most competitive virtue, particularly at a time when as the solar market is being rocked by plummeting prices for photovoltaic panels, a competing technology.
Tonopah's design is the largest of its kind, building on precedents set by a pair of smaller solar towers that have been operating in Spain and Arizona. The current project will use thousands of computer-operated poster-size mirrors aiming sunlight at a tower that absorbs it as heat. After that the absorbed heat is stored in the molten salt, which can be used immediately to boil water, generating steam that turns a conventional turbine and generator. Hot salt can also be used to retain the heat for many hours for later use. BrightSource heats water that can be used immediately as steam or to heat salt for storage.
The plants rely on salt because it can store far more heat than water can. But once molten, it must be kept that way or it will freeze to a solid in part of the plant where it will be difficult to melt again.
This comes after the failure of Solyndra, which was granted $535 million federal loan guarantee to commercialize a novel design for tube-based solar panels. Critics have gone on the warpath, questioning practically all renewable-energy projects that have received federal funds. SolarReserve was offered a $737 million loan guarantee by the DOE last May to help build the Tonopah project.
The 110 MW solar thermal power tower plant utilizing the advanced molten salt system technology from United Technologies Corporation when completed, the facility will supply approximately 480,000 megawatt hours annually of clean, renewable electricity. It is financially backed by a signed 25-year power purchase agreement with NV Energy. Once constructed, it will power up to 75,000 homes during peak electricity periods.
If solar energy is eventually going to matter — that is, generate a significant portion of the nation’s electricity — the industry must overcome a major stumbling block, experts say: finding a way to store it for use when the sun isn’t shining. That challenge seems to be creating an opening for a different form of power, solar thermal, which makes electricity by using the sun’s heat to boil water. The water can be used to heat salt that stores the energy until later
Sources:
Digg Topnews
NYTimes.com
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